In an electronic device, such as a server, there are installed integrated circuits (ICs) and electronic components that use a higher voltage than a power supply voltage or a lower voltage than the power supply voltage as an input voltage, and thus a power supply apparatus including a direct current to direct current (DC/DC) converter that raises or lowers the power supply voltage is installed in the electronic device. The DC/DC converter includes a switching control unit that detects an output voltage and generates a switching control signal, a switching element that performs on and off switching in response to the switching control signal, and a smoothing electrolytic capacitor that outputs a charge voltage as power.
There is known a life detection apparatus that determines approach of the end of life of an electrolytic capacitor included in a DC/DC converter. In an example, the life detection apparatus includes a frequency measurement unit, a comparison unit, and a life notification unit. The frequency measurement unit measures a frequency of a switching control signal. The comparison unit compares the frequency measured by the frequency measurement unit with a preset threshold value. The life notification unit provides a notification that the electrolytic capacitor is approaching the end of its life when the frequency measured by the frequency measurement unit exceeds the threshold value. For example, see Japanese Laid-open Patent Publication No. 2013-38847.
There is also known a method in which an alternating-current voltage is applied to an electric double layer capacitor and an impedance characteristic based on a frequency of the applied alternating-current voltage is measured so as to determine degradation of the electric double layer capacitor. A determination of degradation of the electric double layer capacitor is made by obtaining an inflection point appearing in an impedance characteristic due to degradation of an electrolytic solution in advance and comparing impedance values in a frequency region lower than this inflection point. For example, see Japanese Laid-open Patent Publication No. 2006-47283.
Other examples of the related art include Japanese Laid-open Patent Publication No. 2008-306850, Japanese Laid-open Patent Publication No. 2009-195044, Japanese Laid-open Patent Publication No. 2011-188649, and Japanese Laid-open Patent Publication No. 2011-109823.
In a known technique for determining whether the end of life of an electrolytic capacitor has been reached, there is provided an apparatus that generates an input signal used when a determination as to whether the end of life has been reached is made, or a detector for detecting a physical quantity used for determining whether the end of life has been reached. For example, the above-mentioned life detection apparatus includes the frequency measurement unit that measures a frequency of a switching control signal, and, in the method for determining degradation of the electric double layer capacitor, there is provided an apparatus that applies an alternating-current voltage to the electric double layer capacitor.
In the known technique, there is a problem in that the cost of manufacturing a power supply apparatus is increased because a device used for determining whether the end of life of an electrolytic capacitor has been reached is disposed in the power supply apparatus.
In one embodiment, an object is to provide a new technique that enables a determination of degradation of an electrolytic capacitor without addition of a sensor or circuit.